import "/std";

println("Iterative Fibonacci example");

let fib = (n: I32) {
    let mut prevprevn = 0;
    let mut prevn = 0;
    let mut curn = 1;

    let mut i = 2;

    while i <= n {

        prevprevn = prevn;

        prevn = curn;

        curn = prevprevn + prevn;

        i = i + 1;

    };

    curn
};

print("Enter a number: ");
let n = read_num();

let fib_number: I32 = fib(n);

let output = if fib_number != fib(14) {
        fib_number
    } else {
        println("Input was 14 so result will be negated for demonstration");
        -fib_number
    };

print("Fibonacci of ");
printn(n);
print(" is ");
printnln(fib(n));
println("");